1. Field of Invention
The present invention relates to dispensing devices and more particularly to an improved liquid soap dispenser.
2. Related Art
Liquid soap dispensers are generally classified as stand soap dispenser and wall mounted soap dispenser. A conventional stand type liquid soap dispenser is shown in FIGS. 1 and 2 and comprises a container (e.g., one made of plastics) 1 with supply of liquid soap contained therein, a hollow nut A is mounted on a top opening of the container 1, a hollow cylinder 11 having an upper portion mounted at the container opening by the nut A, a ring 13 mounted on top of the cylinder 11, a sliding spout tube 14 provided through the ring 13, the nut A, and the container opening to be fastened by a positioning member 131, a plunger 17 including a shaft 171 extended from its intermediate disk-shaped member downwardly into its internal space, an intermediate annular groove 172 formed on the disk-shaped member and being in fluid communication with an internal space of the cylinder 11, and an upper soap tube 173 having a top connected to a bottom of the cylinder 11, a spring S having an upper portion put on the shaft 171 and a lower portion biased against a bottom of the cylinder 11, a seal 18 slidably provided between the soap tube 173 and an inner surface of the cylinder 11, an inner tube 12 having a top end secured to an underside of the cylinder 11 and a lower end extended into the supply of soap, a pump handle 16 mounted on a top of the spout tube 14, and a spout 15 formed at an open end of the handle 16.
In an inoperative position, both the soap tube 173 and the groove 172 are closed by the seal 18. For dispensing soap, a user may depress the handle 16 and thus the spout tube 14 as indicated by arrow P. Also, the seal 18, the disk-shaped member of the plunger 17, and the spout tube 14 lower with the spring S being compressed in the cylinder 11 by the disk-shaped member of the plunger 17. But the downward moving distance of the seal 18 is smaller than that of the spout tube 14. Thus, a gap is formed between the seal 18 and the groove 172 (i.e., a vacuum is created). Then soap is drawn from the supply of soap to the soap tube 173 through the inner tube 12, the cylinder 11, and the groove 172. Finally, soap flows out of the spout 15 from the soap tube 173 through the spout tube 14.
However, the prior art suffered from a disadvantage. For example, amount of soap flowing out of the spout 15 may decrease as the remaining amount of the supply of soap decreases. That is, less soap is dispensed as pumping times increases. It is often that a user even cannot pump out any soap when the supply of soap is below half of its full capacity. This is because the created vacuum decreases as distance between a top of the spring S and liquid level increases (i.e., supply of soap gradually consumed). Thus, the need for improvement still exists.